Best Fit Line by Least Squares

Function

This command will sample a group of points by screen selection or point number range, and then compute the best fitting line by least squares. There are options to best fit with nothing held (None), to best fit by holding a point, and to best fit by holding a bearing. All three options are shown below in the graphic. When holding a point, you are prompted to enter the weight for the point. In this example, a weight of 1000 caused the line to pass to within 0.025 of point 111. With a weight of 5000, the line passed to within 0.005 of point 111. Increase the weight accordingly to obtain the desired precision. When holding a bearing such as N45E, you are prompted to enter the bearing in the form QDD.MMSS (e.g. 145.0000 or just 145). The program generates a standard report.

Prompts

Select points from screen, group or by point number [<Screen>/Group/Number]? S
Select Carlson Software Points.
Select objects: pick the five points
Point numbers (Enter to continue): press Enter
Parameter to hold [<None>/Point/Bearing]: P
Enter point number to hold:111
Enter weight for point: 5000

Sample Report:

Best Fit Line By Least Squares 05/14/2006 18:15
Holding point 111: (5227.721,5149.482)

Coordinate File> c:\scad2006\data\interval.crd

Source Coordinates
Point# Northing  Easting   Residual
109    5103.542  5182.098  10.050
110    5114.634  5191.928  6.921
111    5149.482  5227.721  0.005
112    5178.703  5268.237  0.400
113    5201.666  5312.602  8.129

Residuals Standard Deviation: 6.559

Bearing: N 53°44'07" E
Distance: 163.266

Pulldown Menu Location: COGO
Keyboard Command: bfitlinelq
Prerequisite: Group of points to sample
File Name: \lsp\bfitlr.lsp